Selenium yeast product, a method of preparing a selenium yeast product and the use of the product for preparing food, a dietary supplement or a drug

ABSTRACT

A selenium yeast product for use in food, dietary supplements or drugs containing significant and homogeneous amounts of easily digestible organically bound selenium, in which the content of selenium compounds is in the range of between 1000 and 1600 ppm, and in which product the content of 1-selenomethionine constantly constitutes at least 55% of the total selenium content, and in which product the content of selenium in inorganic selenium compounds does not exced 1% of the total selenium content. Furthermore, a method of preparing a selenium yeast product for use in food, dietary supplements, or drugs whereby said yeast is cultivated on a minimal medium under aerobic conditions, while nutrients are added to the yeast during the cultivation to an extent corresponding to the consumption of said nutrients in the yeast; glucose and/or maltose are the sole sources of carbon in the feeding medium.

TECHNICAL FIELD

The present invention relates to a selenium yeast product for use infood, dietary supplements or drugs, said product containing significantand homogeneous amounts of easily digestible and tolerable, organicallybound selenium. The invention also relates to a method of preparing saidselenium yeast product as well as the use of the selenium yeast productfor preparing food, a dietary supplement or a drug.

BACKGROUND ART

Selenium is an element essential to human nutrition. Selenium isingested through the diet, which, however, has a varying content ofselenium. In large parts of the world, crops with poor levels ofselenium are cultivated because the presence of said element in the soilis modest.

The importance of selenium to humans has been substantiated through agreat number of tests. Selenium is incorporated into different organicmolecules, including in particular amino acids. 1-selenomethionine,selenocysteine, selenocystine and selenocystine are the most importantcompounds. Thus, selenium is part of proteins, which are of structuralimportance to the body. Furthermore, selenium is an important ingredientin a number of enzymes which influence the metabolism, the reproduction,the prevention of cancer, the immnune defence and the psyche of humans.viz. Rayman, M., The importance of selenium to human health, Lancet356:233-241 (2000).

Due to the often insufficient content of selenium in the ordinary diet,it is advantageous to add selenium in form of enrichment, dietarysupplements or drugs. These may include an inorganic selenium such asselenite, or they may include organic sources, including selenium yeast.There is a significant difference between absorption and toxicity ofinorganic and organic selenium, the inorganic compounds usually beingabsorbed significantly slower and also being more toxic than organicsources of selenium. An often used source of organic selenium is yeastwith selenium content.

When cultivating yeast, it is possible to add the nutrient mediumselenium in form of inorganic compounds, including sodium selenite andsodium selenate. The selenium added to the nutrient medium in this wayis largely absorbed by yeast and incorporated into organic compounds,including 1-selenomethionine.

Selenium yeast may be prepared by use of a number of yeast species,including Saccharomyces charomnyces cerevisiae, Saccharornyces boulardiisequela and Saccharomyces torula, and by use of different cultivationconditions. As a result, a variable selection of organic compounds ofselenium can be formed in the yeast. The reproducibility obtained byknown methods can be unsatisfactory. A poor reproducibility has caused areluctance to use selenium yeast by authorities, researchers andconsumers. The Scientific Committee on Foods states that the1-selenomethionine content in selenium yeast varies between 20 and 50%,viz European Commission, Scientific Committee on Food, Opinion onsubstances for nutritional purposes which have been proposed for use inthe manufacture of foods for particular nutritional purposes, viz.“PARNUTS”, 12 May 1999, page 5. Scientific Committee on Food on theTolerable Upper Intake Level of Selenium, 11 Oct. 2000, page 2. It is ofvital importance to the use in dietary supplements or drugs that theessential compounds of selenium, viz. species, are present in ahomogenous concentration. This allows long-term studies of theimportance of selenium to be carried out where the reproducibility fromproduction to production is of essential importance for interpreting andusing the results from the studies.

As a cormnercial product, selenium yeast is generally prepared bycultivating on molasses which have varying compositions. It is knownfrom literature that different types of selenium yeast cause varyingabsorption levels and thus deviating responses, viz. Clausen, J. et al.,A comparison of ten selenium supplementation products, Selenium inMedicine and Biology, Walter de Gruyter & Co 305-14 (1988). A number ofpatents describe the cultivation of selenium yeast containing differentconcentrations of selenium Thus, U.S. Pat. No. 4,530,849 discloses thecultivation of selenium yeast with approx. 1000 ppm of selenium.However, the patent does not disclose how the selenium is bound in theyeast or to which extent the method can be reproduced.

Patent application WO 98/37172 relates also to the cultivation and theuse of selenium yeast. The method by cultivation includes the steps ofadmixture of a water-soluble salt of selenium with a nutrient mediumfollowed by the addition of an aqueous suspension of yeast. Theresulting selenium yeast has a selenium content, which is not dividedinto constant, homogeneous compounds. The possibility of obtaining ahomogeneous yield and composition of selenium compounds is not describedeither.

It is a known fact that yeast and other microorganisms can be cultivatedon a medium containing a minimum level of nutrients, a so-called minimalmedium. However, such a method is not usually used industrially becauseit might result in a poor yield and an undesired composition of themicroorganisms. Thus, it is surprising that it is possible bycultivation on a minimal medium in accordance with the present inventionto obtain a good yield and a reproducible composition of selenium yeastwhich is optimal in human nutrition.

Thus, the present invention relates to a method of preparing a yeastproduct containing significant and homogeneous amounts of digestible,organically bound selenium. The resulting yeast is a powder which may beused directly or compressed into tablets by conventional techniques.These tablets can be marketed as food, dietary supplements or drugs.

BRIEF DESCRIPTION OF THE INVENTION

In a first aspect, the invention thus relates to a selenium yeastproduct for use in food, dietary supplements or drugs, said productbeing characterised by having a content of organic selenium compoundscorresponding to between 1000 and 1600 ppm, preferably between 1100 ppmand 1500 ppm, most preferably between 1200 ppm and 1400 ppm of selenium,and by the content of 1-selenomethionine constantly constituting atleast 55% of the total selenium content, and by the content of seleniumin inorganic selenium compounds not exceeding 1% of the total seleniumcontent.

The resulting product is furthermore characterised by a human absorptionof more than 85%.

In a second aspect, the invention relates to a method of preparing aselenium yeast product for use in food, dietary supplements or drugs,whereby the yeast is cultivated under aerobic conditions, said methodbeing characterised by

-   -   i) nutrients being fed to the yeast during the cultivation to an        extent corresponding to the consumption of said nutrients in the        yeast;    -   ii) glucose and/or maltose being the only sources of carbon in        the feeding medium;    -   iii) the concentration of ethanol during the cultivation not        exceeding 1%, preferably 0.5% and most preferably 0.2%;    -   iv) the pH value during the cultivation being maintained at        between 4.0 and 6.0, preferably between 4.4 and 5.7, most        preferably between 4.7 and 5.4, such as 5.0; and    -   v) the feeding medium being mixed with an aqueous salt of        selenium in an amount corresponding to between 1000 and 1500 ppm        of selenium, calculated on dry matter in the yeast.

In a third aspect, the invention relates to a selenium yeast productprepared by the method of the invention.

In a fourth aspect, the invention relates to food, a dietary supplementor a drug including a selenium yeast product according to the invention.

In a fifth aspect, the invention relates to the use of the seleniumyeast product according to the invention for preparing food, a dietarysupplement or a drug.

BRIEF DESCRIPTION OF THE INVENTION

Prior to the detailed description of the different embodiments of theinvention, a number of relevant definitions specific to the main aspectsof the invention are provided below.

Definitions

Minimal medium: Medium containing the rninimum amount of nutrientsnecessary for obtaining yeast growth.

Pharmaceutical quality: Properties of products described in a nationalpharmacopoeia

Starting medium: Mixture of water and additional nutrients seeded withyeast

Feeding medium: nutrients added to the starting medium/culturesubsequent to the pitching of yeast.

The Zak-method: Method of cultivating yeast, whereby said yeast ispitched to a starting medium followed by nutrients being added underaerobic conditions through a feeding medium. The addition of nutrientsis carried out under aerobic conditions at a rate corresponding to theabsorption rate of said nutrients in the yeast. A correct controlresults in a formation of only a small amount of alcohol. The alcoholformed is consumed by the yeast in the last stage of the cultivation.The method is conventional and is referred to as the Z-method. It is asa principle developed by Mr Søren Sak and described in Danish patent No.28507 (1921).

Human absorption: Difference between ingested amount of isotope andexcreted amount of isotope in defecation. Human absorption is calculatedin percent of the ingested amount of isotope.

As mentioned above, hitherto known methods of preparing selenium yeastproducts use primarily molasses as a carbon source and when a glucosebased medium is used, cf. WO 98/37172, this method deviates from themethod of the invention by not ensuring a continuous addition ofnutrients and selenium which corresponds to the cell growth. Inaddition, an admixture of selenium is carried out within a relativelyshort period of time, which complicates the formation of organiccompounds of selenium, which have particular importance in the humannutrition.

The nutrients for the cultivation of yeast according to the inventioninclude sources of carbon and nitrogen as well as micro nutrients inform of vitamins and minerals. The carbon must be in a form which can beingested immediately during the cultivation and therefore it must behighly soluble in water and have a composition allowing a consumption bymeans of the enzymes present in the yeast. These carbon sources includeglucose and maltose which can be purified into glucose syrup in such amanner that they can be used as nutrients for microorganisms producingfood, dietary supplements or drugs. As a source of nitrogen, it ispossible to use inorganic compounds, including ammonia with asufficiently high purity level so as to avoid toxicity or formation ofundesired compounds. The metabolism of the yeast is not completely knownand consequently it is necessary to add micro nutrients in form of yeastextract, which is described in pharmacopoeia.

Thus, yeast can according to the invention be prepared on the basis ofraw materials of a pharmaceutical quality and composed in such a mannerthat the yeast has a minimum level of nutrients which can be used forgrowth. A typical method of cultivating the yeast includes the followingsteps:

-   -   1) Processing the nutrient medium    -   2) Seeding with pitching yeast    -   3) Cultivating    -   4) Harvesting    -   5) Washing    -   6) Heat treating    -   7) Drying

The nutrient medium is produced by dissolving sugar substances, vitaminsand minerals in water heated to between 24 and 37° C., preferablybetween 26 and 34° C., and best between 28 and 32° C. prior to thepitching of yeast.

A seeding with pitching yeast is carried out to the complete and heatednutrient medium by suspending the yeast cells in the medium whilestirring at a frequency of between 1 and 2 Hz. The selenium yeast can beprepared by use of a number of species, including Saccharomycescerevisiae, Saccharomyces boulardii sequela and Saccharomyces torula.Among said species, Saccharomyces cerevisiae is generally considered tobe suitable for human ingestion, and it is widely used for thepreparation of bread and alcohol. For the preparation of a seleniumyeast product according to the invention it is an advantage to use aproduction strain, which is genetically stable and thus less inclined tobe subjected to a mutation. In an embodiment according to the presentinvention, the strain ATCC No 74366 is thus used without, however,limiting the invention thereto.

The cultivation is carried out on the basis of a nutrient medium whichis produced as a particular minimal medium and seeded with the abovepitching yeast. Furthermore, additional carbohydrates are added in formof glucose and/or maltose. An aqueous solution of ammonia is admixed asa source of nitrogen. In order to ensure the highest possible growth andto counteract the formation of alcohol, large amounts of air areintroduced, preferably atmospheric air containing sufficient oxygen. Inlarge scale preparations, it is in practice difficult to ensure acomplete oxidation, which can change the nutrition need of the yeastslightly. Cultivation is terrninated at a concentration of yeast ofapproximately 4% by weight, calculated on the total content of nutrientmedium and yeast. The addition of nutrients is carried out under aerobicconditions at a rate corresponding to the absorption rate of saidnutrients in the yeast. As a result, only a small amount alcohol isformed through a correct control. The alcohol formed is consumed by theyeast in the last stage of the cultivation.

In practice, the addition of nutrients in the correct amount iscontrolled by continuously measuring the amount of alcohol in form ofethanol formed during the growth. If the nutrients are added too slowly,no alcohol is formed and if the addition is carried out too fast,significant amounts of alcohols are formed. Therefore, the amount ofalcohol present at any time should not exceed 1%, preferably 0.5% andmost preferably 0.2%. Furthermore, the pH of the growth medium can beused as an indicator for maintaining the correct balance betweenconsumption and addition of nutrients, and therefore the pH iscontrolled and adjusted during the growth so as to maintain the pHbetween 4.0 and 6.0, preferably between 4.4 and 5.7, most preferablybetween 4.7 and 5.4, such as 5.0.

The harvest involves a separation of the cultivated yeast from thenutrient medium. This separation is best achieved by centrifuging,whereby a concentrated yeast cream is produced containing approximately20% by weight of yeast

The purpose of a washing is to remove the excess of nutrients in theyeast cream. The washing is most advantageously carried out by addingwater followed by a centrifuging so that a yeast cream is produced. Inthis way, the yeast is washed 2 to 6 times and preferably 4 times,whereby practically all extracellular nutrients are removed from theyeast cream.

The purpose of the heat treatment is to kill the yeast cells so that theselenium present therein becomes available for the human digestion. Aheat treatment results also in an extensive disintegration of the yeastcells. An advantageous heat treatment can be carried out as apasteurization in a plate heat exchanger at a temperature of 87° C. anda standing time of 30 seconds.

The yeast can be dried by conventional methods of drying organicmaterial including freeze drying, drum drying, tray drying or spraydrying, preferably spray drying. A spray drying removes water at aninput temperature for air of between 160 and 240° C., preferably between180 and 220° C. and best about 200° C. The output temperature can inthis connection be from 70 to 90° C., preferably 80 to 90° C. and bestabout 86° C. The resulting powder has a water content of between 4 and9%, preferably between 6 and 9% and best about 8%. The powder cansubsequently be treated by way of moistening with water and followed bya drying so as thereby to improve the capability to absorb water lateron.

Selenium yeast according to the invention can be used for preparingfood, dietary supplements or drugs, either as the only source ofselenium or in combination with other selenium containing ingredients.

Thus, the invention also relates to food, a dietary supplement or adrug, which as a source of selenium uses the selenium yeast according tothe invention.

In an embodiment of the invention, the use includes a product includinga disintegrating agent, a flow agent as well as selenium yeast. Thismixture is compressed into a tablet containing between 25 and 800 μg ofselenium, particularly between 40 and 300 μg of selenium and especially50 to 200 μg of selenium per tablet

However, in addition to the scope of application described above theinvention can also be used for other types of food to be enriched withselenium such as flour, other powdery food as well as drinks.

The invention is explained in detail below with reference to thefollowing examples.

EXAMPLES Example 1

1 a)

In this example, a fermentor with a volume of 0.014 m³ is used.

At the beginning of the cultivation, a nutrient medium is prepared withthe following composition of raw materials of a pharmaceutical quality:Water Ph. Eur. 5,400 g Glucose syrup Ph. Eur.  31.8 g KH₂PO₄ Ph. Eur.  25 g Ammonia water 2.5% Ph. Eur.   114 g Biotin (0.01%) Ph. Eur.  2.1ml Thiamine hydrochloride (1.0%) Ph. Eur.  2.5 ml Calcium pantothenatePh. Eur.  0.08 g Yeast extract USP   75 g Iron sulphate Ph. Eur  0.10 gMagnesium sulphate Ph. Eur.  5.0 g Manganese sulphate Ph. Eur. 0.033 gZinc sulphate Ph. Eur 0.033 g

Subsequent to adjusting the temperature at 30° C., 5 g of pitching yeastis admixed. The seeded nutrient medium is blown through with sterileatmospheric air in an amount of 20 litres per minute. A stirring iscarried out by means of a spindle at a frequency of 17 Hz. Sulphuricacid is used to adjust the pH so as to maintain the pH at between 4.7and 5.4. It is controlled that ethanol does not exceed 0.2%, and inaddition the concentration of ethanol is maintained as close to 0 aspossible.

During the cultivation, nutrients are added with the feeding medium inthe following amounts: Glucose syrup Ph. Eur 1,060.5 g Ammonia water2.5% Ph. Eur.   1,451 g

In addition, sodium selenite is admixed in ammonia water 2.5%, asfollows: Sodium selenite Ph. Eur 1.2758 g

Glucose syrup, ammonia water and sodium selenite are added at a ratecorresponding to the consumption rate of the substances in the yeast.This is controlled by continuously measuring the formation of alcohol.The concentration of alcohol is maintained close to 0.

The addition of ammonia water (2.5%) is terminated after 18 hours. After19 hours, the cultivation is terminated.

The harvest of the yeast is carried out by transferring the medium withthe yeast to a centrifuge wherein the yeast cream is separated from theexcess medium within 5 minutes. The resulting yeast cream with a drymatter content of approx. 20% is admixed 5,000 g of water. Subsequently,the yeast mixture is centrifuged again. The washing water is removed andthe resulting yeast cream is admixed 5,000 g of water. The process isrepeated 4 times to separate the yeast cells from the medium.

The washed yeast cream is carried through a plate pasteurizer in whichit is subjected to a heat treatment at 87° C. with a standing time of 30seconds. Immediately after the heat treatment, the yeast cream is cooledto 4° C. in a plate pasteurizer. The amount of yeast cream is 1,897.5 g.

The yeast cream is transferred to a freeze dryer. Subsequent to freezingat −40° C. for 24 hours, the water sublimes within 18 hours. 380 g ofdried selenium yeast is hereby provided having a water content of 0.2%and a concentration of selenium of 1,380 ppm in dry matter. The dietaryproperties and the reproducibility of the resulting selenium yeastproduct prepared are determined in the manner described below inExamples 2, 4 and 5.

1 b)

Yeast is prepared in accordance with Example 1a above. However, afermentor with a volume of 150 m³ is used. The nutrient medium iscomposed of corresponding ingredients in the same mutual proportions andhas a total weight of 56,848 kg.

Glucose syrup and ammonia water 2.5% are added in the same way as inExample 1 a. For this purpose, 13,500 kg of glucose syrup and 1,410.5 kgof ammonia water 25% are used. Selenium in form of sodium selenite isadmixed in an amount of 15 kg. The addition of ammonia water isterminated after 18 hours and the cultivation is terminated after 19hours.

The washing and the heat treatment of the yeast are carried outaccording to the principles described in Example 1a.

The drying of the yeast is carried out by spray drying in a drying towerhaving a rotating sprayer wheel. The frequency of the sprayer wheel isset at 167 Hz The air temperature for drying is set at 200° C. Theresulting starting temperature is 86° C. The total amount of powder witha water content of 7% is 5,035 kg. The concentration of selenium is1,355 ppm on dry matter. The dietary properties and the reproducibilityof the resulting selenium yeast product prepared are determined in themanner described below in Examples 2, 4 and 5.

Example 2

Digestibility and absorption of selenium yeast.

2 a) In Vitro Digestibility of Selenium

As a basis for determining the in vitro digestibility of selenium yeast,a further development of the method 9.1 of 15 Nov. 1994 of The DanishPlant Directorate for determining the enzyme-digestible organic matterin pigs, viz. EFOS pigs, is used. The method has been changed so as tocorrespond to the conditions of the human digestion. Enzymes, which candecompose cellulose, are thus not included in this in vitro study.

The principle is treatment with pepsin followed by treatment withpancreatin. Undisolved sample material is filtered off and dried. Bycomparing the determinations of selenium in the original sample with thecontent in the filtrate and the retentate, the digestibility of seleniumis calculated. Thus, selenium yeast is mixed at pH 2.0 with pepsin andincubated at 40° C. for 75 minutes followed by treatment with pancreatinat pH 6.8 at 40° C. for 3 hours and 30 minutes. Subsequently, afiltration is carried out by means of vacuum and the selenium content inthe filtrate and the retentate, respectively, is determined. Theselenium content in the filtrate in percent of the total seleniumcontent in the sample is an expression of the in vitro digestibility ofselenium yeast.

A selenium yeast is obtained with the following characteristics:

Digestible selenium: 99%

2 b) In Vivo Absorption and Retention of Selenium

As a basis for determining the in vivo digestibility, selenium yeastaccording to the invention is administered where a stable isotope havinga content of selenium-77 of 99.3% is used for the cultivation. Sincenaturally occurring selenium only contains 7.8% Se-77 and at the sametime contains 49.82% of Se-80, it is possible to determine theproportion in human material originating from such an addition ofisotope by measuring these isotopes via ICP-MS, viz. Inductively CoupledPlasma—Mass Spectrometry.

The determination of in vivo absorption, retention and bioaccessibilityis moreover carried out as follows:

Twelve male participants aged 20 to 55 are administered a single dose ofselenium yeast corresponding to 300 μg selenium-77. The participantscollect faeces and urine for a period of 5 days, and 11 blood samplesare collected during said period. In order to control the collection offaeces and urine, PABA, viz. para-amnino-benzoic-acid, and plastictubes, respectively, are administered which can be recovered in both theurine and the faeces as a control of the collection. The absorbed amountof selenium-77 is determined by comparing the ingestion of selenium-77with the extraction through faeces.

The retention, viz. the retained amount, is determined as administeredtrace amount minus excretion through faeces and urine compared to theadministered trace amount The blood samples are used to describe thepharmaco-dynamics.

The following characteristics for absorption and retention of theselenium yeast according to the invention are obtained:

The absorption is 89%. The retention is 74%.

2 c) In Vivo Dosage/Response at Long-Term Ingestion

A blank experiment was carried out for a continuous period of 2 years. Agroup of 49 persons ingested a tablet each day with a content of 0, 100,200 or 300 μg of selenium in form of selenium yeast according to theinvention. Furthermore, the participants ingested through their food theamount of selenium naturally occurring in the diet, viz. approximately50 μg/day. After 2 years where a balance between absorption andexcretion has been obtained, the selenium content in whole blood wasdetermined.

The following results were found: Mean value of Increase Ingestion perselenium in Absorption of compared day Number of whole blood seleniumper to placebo (μg) participants (μg/l) μg (μg/l/μg) (%) 0 17 95.6 — 0100 11 177.2 0.816 85 200 8 307.6 1.06 222 300 13 440.8 1.15 361

Based on the above results, a linear connection between the ingesteddosage of selenium yeast and selenium content in whole blood could bedetermined and expressed in the following way:Selenium in whole blood (μg/l)=1.12 ×ingestion (μg/day)+38

The discovered response on selenium yeast according to the inventionsurpasses the prior art description of selenium yeast, viz. Schrauzer,G. N., Selenium in human nutrition, Bioinorganic Chemistry, 8:303-318(1978).

2 d) Measurement of Side Effects at Long-Term Ingestion

For a period of 1-2½ years, selenium yeast according to the inventionwas administered in doses of 100, 200 or 300 μg or placebo to 806persons in 4 equally divided groups. The period covers approximately1400 person-years. During this period, the tolerance and the sideeffects were tested in all persons, 2.6%, viz. 21 of the 806 persons,reported side effects. Before the randomization was terminated, the sideeffects were categorised as either mild, 17 persons, moderate, 4persons, or serious, 0 persons.

Subsequent to divulgating the randomization, the side effects turned outto be divided randomly on the groups, 8 relating to placebo, 8 to 200 μgSe and 6 to 300 μg Se. The conclusion was that the side effects wereinsignificant and did not relate to the selenium yeast according to theinvention.

Example 3

Tablet:

Preparation of tablet of selenium yeast according to the invention iscarried out by means of the following ingredients:

Selenium yeast according to the invention

Tablet auxiliaries: microcrystalline cellulose

-   -   silicon dioxide    -   magnesium salts of fatty acids

Flow agent: di-calcium phosphate

Surface-treatment agent: hydroxyl propyl methyl cellulose

-   -   talcum

Colourant: titanium dioxide

The ingredients are mixed in a conventional manner and compressed intotablets so that each tablet contains 100 μg of selenium originating fromselenium yeast.

Example 4

Speciation of selenium yeast

A selenium yeast cultivated in a conventional manner by use of molassesand 2 batches of selenium yeast according to the invention were examinedfor content of various compounds of selenium. The samples were subjectedto acid hydrolysis with thioglycolic acid as stabilizer in oxygen-freesurroundings. The content of selenomethionine and sodium selenite wasthen determined by HPLC against laboratory references.

The selenium yeast cultivated on molasses had a content of 49% ofselenomethionine of the extractable and HPLC-accessible part, while theselenium yeast according to the invention in two independent productionbatches showed a content of 72.8 and 72.9%, respectively, ofselenomethionine of the extractable and HPLC-accessible part.

The extractable part of total selenium exists as 95 to 101%, of whichapproximately 80% can be tested by means of HPLC. The minimum trueamount of 1-seleno-methionine of total selenium is thus72.8%×95%×80%=55.3%. The highest possible true amount is approx. 90%.The measured amount of sodium selenite is less than 1%. It is possibleto use a method described by Erik. H. Larsen et al., viz. Larsen, E. H.et al., J. Anal. At. Spectrom., 16, 1403-1408, 2000, for determiningspecies of selenium.

In the Example, importance is attached to the reproducibility ratherthan to the actual true amount.

Example 5

In vivo absorption of selenium yeast and inorganic selenium

In the same way as in the application Example 2b, either selenium yeastaccording to the invention or inorganic selenium-77 was administered tothe same 12 test persons. The human absorption of the two sources ofselenium was 89% for selenium yeast according to the invention and 23%for inorganic seleniurn, respectively.

1. A method of preparing a selenium yeast product for use in food,dietary supplements, or drugs, whereby said yeast is cultivated on aminimal medium under aerobic conditions, comprising the steps of a)cultivating the yeast, which includes i) nutrients being fed to theyeast during the cultivation to an extent corresponding to theconsumption of said nutrients in the yeast; ii) glucose and/or maltosebeing the sole sources of carbon in the feeding medium; iii) theconcentration of ethanol during the cultivation not exceeding 1%,preferably 0.5% and most preferably 0.2%; iv) the pH value during thecultivation being maintained at between 4.0 and 6.0, preferably between4.4 and 5.7, most preferably between 4.7 and 5.4, such as 5.0; and v) anaqueous salt of selenium being admixed to the feeding medium in anamount corresponding to between 1000 and 1500 ppm of selenium,calculated on dry matter in the yeast; b) isolating the yeast obtainedin step (a).
 2. A method according to claim 1, further comprising theisolation including harvest by way of centrifuging or filtration.
 3. Amethod according to claim 1, further comprising including the steps of:c) washing the yeast cells from step (b), d) heat treating the yeastcells from step (c), and e) optionally drying the product from step (d).4. A method according to claim 1 further comprising the minimal mediumbeing composed of raw materials of a pharmaceutical quality.
 5. A methodaccording to claim 1 further comprising the yeast including a species ofthe genus Saccharomycetaceae, preferably Saccharomyces cerevisiae,Saccharomyces boulardii sequela and/or Saccharomyces torula.
 6. A methodaccording to claim 5, wherein the yeast is Saccharomyces cerevisiae. 7.A selenium yeast product for use in food, dietary supplements or drugs,comprising a) a content of organic selenium compounds corresponding to arange of between 1000 and 1600 ppm of selenium, preferably between 1100ppm and 1500 ppm of selenium, most preferably between 1200 ppm and 1400ppm of selenium, b) the content of 1-selenomethionine constantlyconstituting at least 55% of the total selenium content, and the contentof selenium in inorganic selenium compounds not exceeding 1% of thetotal selenium content, c) the selenium yeast product being obtainableby cultivating a yeast culture seeded with a pure culture of aSaccharomyces sp., preferably S. cerevisiae, S. boulardii sequela,and/or S. torula, by adding sources of carbon, nitrogen and selenium inamounts per time unit corresponding to the amount which can be absorbedin the yeast during a predetermined time period, and the cultivationtaking place in minimal medium exclusively including purified,homogeneously defined nutrients in form of raw materials which aredescribed in pharmacopoeia.
 8. A selenium yeast product according toclaim 7, comprising producing said selenium yeast product by the methodaccording to claim
 1. 9. A method for preparing a food productcomprising adding said selenium yeast product according to claim 7 tosaid food product.
 10. A method for preparing a dietary supplementcomprising adding said selenium yeast product according to claim 7 tosaid dietary supplement.
 11. A method for preparing a drug comprisingadding said selenium yeast product according to claim 7 to said drug.